Fig. 5: Energy level relaxation characteristics. | Light: Science & Applications

Fig. 5: Energy level relaxation characteristics.

From: Towards high-power mid-IR light source tunable from 3.8 to 4.5 µm by HBr-filled hollow-core silica fibres

Fig. 5

a Boltzmann distribution in the v = 2 vibrational state. Measured output spectra changing with gas pressure when pumped at the R(7) line with 6.2 W pump power for the H79Br isotope (b) and H81Br isotope (c). d Schematic of population transition. The red lines show that the first overtone R(7) absorption results in fundamental R(7) and P(9) emissions. The blue lines show that the R-R relaxation results in the fundamental P(4) and P(5) transitions. e, f Measured output spectra changing with incident pump power at a gas pressure of 8.2 mbar when pumped at the R(7) line for the H79Br isotope (e) and H81Br isotope (f)

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